Can't import the 'Serial' library to connect with Arduino
I have found my problem (windows):

I was using and installing 32bits python and 64 bits from blender.

My solution:


I'm using Windows 10 64 bits.
Download Blender 32 bits,v2.79.
Remove/uninstall all Python stuff that i have.
Reboot the system.
Reinstall Python 3.5.3 (64-bits) donwloaded from Python site.
Download the pyserial, version 3.4.
Copy from pyserial: the folder serial, paste the folder in blender sub-folder site-packages: 
 /blender-2.79b-windows32/2.79/python/lib/site-packages
Open and run Blender 32 bits,v2.79.
Using Blender game engine, made a script and my LED in Arduino turned on.